Congenital Anomaly Diagnosis of Typical Cardiac Chest Pain Due to Thebesian Veins Draining Into the Left Ventricular Chamber: A Case Report and Review of Literature

Thebesian veins are microfistulae that drain the coronary arteries directly into one or more chambers of the heart. Persistence of these anomalous connections into adulthood can lead to shunting of blood away from the myocardium causing typical chest pain symptoms with electrocardiogram changes consistent with ischemia. We describe a case of a 77-year-old female who underwent ischemic evaluation for her symptoms found to have significant Thebesian veins. We also engage in a comprehensive review of the literature finding consistencies in the way these cases are presented in the literature.


Introduction
The Thebesian venous system is formed by small fistulous passages draining a coronary artery directly into the atrium or ventricle [1].This venous system is a rare anomaly found on coronary angiography [2].The majority of patients with these microfistulae remain asymptomatic although some go on to develop ischemia through the phenomenon of coronary steal [3].First described in 1706 by Vieussens, these primitive venous vessels supply the subendocardial tissue of the myocardium during early embryonic development [4,5].Interruption during this period leads to the persistence of these venous channels through adulthood creating a pathway where the blood is not able to reach the more finer capillaries of the myocardium.Herein, we report a case of a 77-year-old female with a rare anatomic finding of significant Thebesian veins draining into the left ventricular (LV) chamber presenting with typical anginal symptoms.We also engage in a review of literature of cases published in the literature finding similarities in the way these cases present.

Case Presentation
A 77-year-old female with a past medical history significant for hypertension, hyperlipidemia, a 50-packyear smoking history, and a family history of premature coronary artery disease presented in the outpatient setting with complaints of intermittent left-sided chest pain worse with exertion and relieved with rest.Her electrocardiogram (EKG) revealed T wave inversions in the septal leads (Figure 1).A transthoracic echocardiogram revealed an LV ejection fraction of 45-50% with mild global hypokinesis.Given her significant cardiac risk factors and strong family history of coronary artery disease, she was taken to the cardiac catheterization laboratory for a coronary angiogram to rule out ischemic heart disease.On coronary angiography, the dominant right coronary artery and left main were angiographically free of disease.Injection of dye revealed a capillary blush in the LV chamber with the left circumflex artery system providing significant Thebesian veins draining into the LV cavity (Figure 2).She was conservatively managed with aggressive risk factor modification and medical management comprising of aspirin 81 milligrams (mg) daily, carvedilol 6.25 mg twice a day, and atorvastatin 20 mg daily and scheduled to follow-up in the outpatient setting in one month.

Methods
We conducted a comprehensive literature search of all reported cases of Thebesian veins on PubMed, Embase, and Google Scholar between the years 1999 and 2023 using the keyword "Thebesian veins."We did not enforce any language restriction.A total of 45 cases were retrieved.

Data of Interest
Age, sex, clinical presentation, electrocardiogram (EKG) findings, serum troponin, and coronary angiographic findings were extracted.Mean age and standard deviation were calculated.Serum troponin was categorized as being normal or elevated.EKG descriptions for each case were analyzed and classified as having T wave inversions versus no T wave inversions.

Results
The age range was 52 to 91 years with a mean of 71.9 (SD ±10.7).Of the patients, 31 (71%) were females.Chest pain was the most commonly reported symptom seen in 27 (60%), followed by shortness of breath (11, 24%) and palpitations (5, 11%).Troponin elevation was seen in nine (20%) patients.A total of 18 (40%) cases had T wave inversions in the precordial leads on EKG.The most common fistulous connection identified was between the branches of the left coronary artery (LCA) draining into the left ventricle (LV) seen in 42 (93%) individuals.
Thebesian vessels help drain the blood supply of the myocardium by directly connecting branches of the coronary artery to the atrial and ventricular cavities.These veins, which are part of the lesser cardiac venous system, can rarely present with cardiac chest pain.Symptoms occur when they drain a substantial amount of blood into the chambers of the heart.A coronary fistula occurs when an aberrant connection between a coronary artery and either a vein, another artery, or one of the heart chambers exists [6].Thebesian veins are an integral part of the congenital cardiovascular system; however, they contribute only minimally to heart circulation in adults [1].They are rarely extensive enough to cause shunting of the coronary vascular system, meaning the blood supplying the heart takes an alternate abnormal path forming a loop that diverts blood away from the favored capillary network of the myocardium.These aberrant pathways can then cause patients to have symptoms of angina, shortness of breath, or even acute coronary syndrome (ACS) in some cases.ACS tends to occur due to the phenomenon of coronary steal leading to decreased blood supply to the myocardium [7].An estimated 0.08%-0.3%have a solitary coronary artery draining into a cardiac chamber, while all three major coronary arteries emptying into a cardiac chamber are even rarer [7].They have clinical implications in selective cases [8].
EKG changes noted in our patient replicated those described in the literature in patients with extensive Thebesian veins [1,3,6,7].The literature also suggests troponin elevation may be present in some but not all patients [1,3,6,9].Frank et al. have also suggested that when Thebesian veins cause hemodynamic instability they can mimic EKG changes comparable to Wellens syndrome [10].
When extensive, Thebesian veins can be detected through an echocardiogram with Doppler and cardiac MRI.However, they are most reliably diagnosed with coronary angiography.Heart catheterization showed evidence of Thebesian veins emptying into the left ventricular chamber in the majority of published case reports, with our review showing up to 90% of cases having fistulous connections draining into the LV chamber [1,3,6,9].Medical management comprises beta blockers and nitrate vasodilators [7].There is a risk of augmenting the coronary steal phenomenon with nitrate therapy, thus making the use of nitrates controversial [1].The use of renin-angiotensin-aldosterone system blockers has also been mentioned in the literature [11][12][13].From a surgical perspective, treatment options are limited to coronary artery bypass grafting or trans-myocardial laser revascularization (TMLR).In addition, managing existing comorbidities and risk factors related to coronary artery disease is crucial.Published case reports are summarized in Table 1.

Conclusions
Our case with a relevant review of the literature adds to the growing body of evidence of Thebesian veins as a cause of myocardial ischemia presenting with typical chest pain signs and symptoms.Further research is required to understand how this anomaly can affect long-term outcomes and how optimal care can be provided to individuals with this rare anomaly.

FIGURE 2 :
FIGURE 2: Coronary angiography findings Coronary angiography of the left main coronary artery, left anterior descending artery, and left circumflex artery.(A) The left circumflex artery filling the Thebesian veins through the myocardium, which is outlined by the arrows.(B) Thebesian veins, outlined by the arrows, filling the left ventricular cavity during systole.